The present invention relates to an apparatus and a method for conveying a rectangular stimulable phosphor sheet which is favorably employable for conveying the stimulable phosphor sheet with change of its conveyed course in a radiation image recording and reproducing system.
As a method replacing a conventional radiography, a radiation image recording and reproducing method utilizing a stimulable phosphor was proposed and has been practically employed. The method employs a rectangular stimulable phosphor sheet (i.e., rectangular radiation image storage panel) comprising a stimulable phosphor, and comprises the steps of causing the stimulable phosphor of the phosphor sheet to absorb radiation energy having passed through an object or having radiated from an object; sequentially exciting the stimulable phosphor with stimulating rays to release the radiation energy stored in the phosphor as light emission (i.e., stimulated emission); photoelectrically detecting the stimulated emission to obtain electric signals; and reproducing the radiation image of the object as a visible image from the electric signals. The phosphor sheet thus treated is then subjected to a step for erasing a radiation image remaining therein, and then stored for the next recording and reproducing procedure. Thus, the stimulable phosphor sheet can be repeatedly employed.
The stimulable phosphor sheet has a basic structure comprising a support and a stimulable phosphor layer provided thereon. If the phosphor layer is self-supporting, the support may be omitted. On the free surface (surface not facing the support) of the phosphor layer, a transparent protective film is generally placed to keep the phosphor layer from chemical deterioration or physical damage.
As is described above, the stimulable phosphor sheet is conveyed step by step for being subjected to various procedures such as irradiation with radiation such as X-rays for recording the radiation image, irradiation with stimulating rays for reading the recorded radiation image, and erasure of radiation energy remaining in the phosphor sheet by applying thereto the erasing light.
In the early stage of the development of radiation image storing and reproducing system, each of the recording procedure, reading procedure, and erasing procedure was performed in a separately manufactured apparatus specifically designed for each procedure. The stimulable phosphor sheet was manually transferred from one apparatus to other apparatuses. In each apparatus, the phosphor sheet was conveyed by a conveyor belt almost in the horizontal direction.
A recently developed compact automated apparatus for performing the radiation image storing and reproducing system affords performing all related procedures within the compact apparatus. In other words, the recording procedure, reading procedure and erasing procedure are all performed in one compact apparatus. In the compact apparatus, the stimulable phosphor sheet is conveyed not only horizontally but also vertically. Moreover, the stimulable phosphor sheet should be turned with sharp angles in such a mode as 90 degree-turn or 180 degree-turn from the horizontal movement to the vertical movement and vice versa.
Published European Patent Specification of EP 0 159 613 B1 describes a device conveying a stimulable phosphor sheet in the vertical direction which comprises two guiding members arranged parallel in substantially vertical direction and a plurality of driving members in the form of rotatable rollers wherein the axis of rotation of the driving members is arranged in a substantially horizontal direction and wherein the distance between two driving members adjoining each other along the vertical direction is smaller than the length of said stimulable phosphor sheet, characterized in that the driving members are rotatable rollers being arranged in pairs, that the phosphor sheet is to be engaged between said pair of driving members, that at least one member of each pair of driving members is connected to a motor and the guiding members are U-shaped and have a distance to each other at least of the transverse dimension of the phosphor sheet for keeping both edges of the phosphor sheet.
The conveying device described in the published EP specification can be employed for conveying the stimulable phosphor sheet in the vertical direction in a radiation image recording and reproducing system. In the published specification, however, no means are described for conveying the stimulable phosphor sheet with change of its conveyed course.
It is an object of the present invention to provide an apparatus for conveying a stimulable phosphor sheet with change of its conveyed course such as 90-degree turn mode or 180-degree turn mode in a radiation image recording and reproducing method.
It is another object of the invention to provide a method for conveying a stimulable phosphor sheet with change of its conveyed course such as 90-degree turn mode or 180-degree turn mode in a radiation image recording and reproducing method.
The present invention resides in an apparatus for conveying a rectangular stimulable phosphor sheet with change of its conveyed course which comprises:
a pair of longitudinal guide plates curved to form an arc, each guide plate being arranged in parallel to each other with a space approximately corresponding to the width of the phosphor sheet;
a series of rollers which are so arranged along each of the guide plates to allow advancement of the phosphor sheet between a guide space formed by the guide plate and these rollers; and
a pair of driving rollers which are arranged in the vicinity of one ends on imaginary plane extended from the pair of the curved guide plates.
The conveying apparatus of the invention preferably further comprises another pair of driving rollers which are arranged in the vicinity of another ends on imaginary plane extended from the pair of the curved guide plates.
The present invention also resides in a method of conveying a rectangular stimulable phosphor sheet with change of its conveyed course by means of a pair of longitudinal guide plates curved to form an arc, each guide plate being arranged in parallel to each other with a space approximately corresponding to the width of the phosphor sheet; a series of rollers which are so arranged along each of the guide plates to allow advancement of the phosphor sheet between a guide space formed by the guide plate and these rollers; a pair of driving rollers which are arranged in the vicinity of one ends on imaginary plane extended from the pair of the curved guide plates, and another pair of driving rollers which are arranged in the vicinity of another ends on imaginary plane extended from the pair of the curved guide plates which comprises the steps of:
drawing the phosphor sheet into the guide space by rotating the driving rollers arranged in the vicinity of one ends and keeping both sides of the phosphor sheet between the guide space;
advancing the phosphor sheet by continuing the rotation of the driving rollers and keeping both sides of the phosphor sheet between the guide spaces;
advancing the phosphor sheet by rotating the driving rollers arranged in the vicinity of another ends and keeping both sides of the phosphor sheet between the guide spaces; and
drawing the phosphor sheet out of the guide spaces by rotating the driving rollers arranged in the vicinity of another ends and keeping both sides of the phosphor sheet between the guide spaces.
The invention further resides in a method of conveying a rectangular stimulable phosphor sheet whose forward end is retracted at its center area, with change of its conveyed course in an apparatus comprising a pair of longitudinal guide plates curved to form an arc, each guide plate being arranged in parallel to each other with a space approximately corresponding to the width of the phosphor sheet; a series of rollers which are so arranged along each of the guide plates to allow advancement of the phosphor sheet between a guide space formed by the guide plate and these rollers; a pair of driving rollers which are arranged in the vicinity of one ends on imaginary plane extended from the pair of the curved guide plates, and another pair of driving rollers which are arranged in the vicinity of another ends on imaginary plane extended from the pair of the curved guide plates which comprises the steps of:
drawing the phosphor sheet into the guide space by rotating the driving rollers arranged in the vicinity of one ends and keeping both sides of the phosphor sheet between the guide space;
advancing the phosphor sheet by continuing the rotation of the driving rollers and keeping both sides of the phosphor sheet between the guide spaces;
advancing the phosphor sheet by rotating the driving rollers arranged in the vicinity of another ends and keeping both sides of the phosphor sheet between the guide spaces; and
drawing the phosphor sheet out of the guide spaces by rotating the driving rollers arranged in the vicinity of another ends and keeping both sides of the phosphor sheet between the guide spaces.
The invention furthermore resides in a method of conveying a rectangular stimulable phosphor sheet whose flexibility in its conveying direction is higher than flexibility in its width direction, with change of its conveyed course in an apparatus comprising a pair of longitudinal guide plates curved to form an arc, each guide plate being arranged in parallel to each other with a space approximately corresponding to the width of the phosphor sheet; a series of rollers which are so arranged along each of the guide plates to allow advancement of the phosphor sheet between a guide space formed by the guide plate and these rollers; a pair of driving rollers which are arranged in the vicinity of one ends on imaginary plane extended from the pair of the curved guide plates, and another pair of driving rollers which are arranged in the vicinity of another ends on imaginary plane extended from the pair of the curved guide plates which comprises the steps of:
drawing the phosphor sheet into the guide space by rotating the driving rollers arranged in the vicinity of one ends and keeping both sides of the phosphor sheet between the guide space;
advancing the phosphor sheet by continuing the rotation of the driving rollers and keeping both sides of the phosphor sheet between the guide spaces;
advancing the phosphor sheet by rotating the driving rollers arranged in the vicinity of another ends and keeping both sides of the phosphor sheet between the guide spaces; and
drawing the phosphor sheet out of the guide spaces by rotating the driving rollers arranged in the vicinity of another ends and keeping both sides of the phosphor sheet between the guide spaces.